Cut 300 g boneless chicken thigh into bitesize pieces and place them in a bowl. Sprinkle with 1 pinch salt and 1 tbsp all-purpose flour, and mix until evenly coated.
Heat a frying pan on medium and once hot, add 1 tsp cooking oil. Place the chicken thigh pieces skin-side down in a single layer and fry until crispy and golden, about 2-3 minutes.
Flip and sear on the other side. When there is no more pink visable, turn off the heat and transfer the chicken to a plate.
Wipe the pan with kitchen paper to remove any excess oil and pour in 100 ml dashi stock, 3 tbsp mirin, 1 tbsp light brown sugar, and 1 tsp Chinese-style chicken bouillon powder. Mix well, then add ½ onion (thinly sliced) to the broth and simmer over medium heat until softened.
Pour 2 tbsp Japanese soy sauce (koikuchi shoyu) around the pan and add the chicken pieces back in, evenly spaced apart.
Separate the whites and yolks of 3 eggs into two bowls.
Whisk the egg whites and pour them around the pan. (Do not add the yolks yet.)
Place a lid on top and cook for a few minutes, or until the whites are just starting to turn opaque.
Reduce the heat to the lowest setting and remove the lid. Whisk the egg yolks and pour them around the pan. Place the lid back on and continue to steam-cook until the eggs reach your preferred doneness. (Authentic oyakodon should have eggs that are only just cooked, slightly runny yolks are recommended.)
Use a spatula to divide the egg into pieces that will fit on top of your serving bowls. Dish up 2 portions cooked Japanese short-grain rice, then use a spatula or large serving spoon to scoop the egg and chicken mixture onto the rice.
Drizzle any leftover sauce in the pan evenly over each portion and garnish with kizami nori (shredded nori) and/or Japanese wild parsley (mitsuba). Enjoy!
Notes
Chicken bouillon powder varies by brand. My brand is 1 tsp per 200 ml, so check the label and if yours is more concentrated (e.g., 1 tsp per 300 ml or 1 cup), use touch less to avoid oversalting.Regular Japanese soy sauce is the default, but you can use usukuchi (Japanese light soy sauce) for a paler, refined look. Use slightly less because it's saltier.Taste the sauce before adding eggs and fine-tune with a tiny splash of soy/sugar/water as needed. It should taste a touch rich because it will be softened by eggs and plain rice.Whites need more heat/time to firm (around 82℃ (180°F)), while yolks thicken sooner (around 70℃ (158°F)), which is why the two-stage approach is consistent.If the eggs firm up too much, spoon a little sauce over the top and serve immediately.This recipe makes 2 standard donburi servings or 4 mini-don (side) servings.Storing leftover is generally not recommended.Meal prep: Prep the chicken/onion and measure seasonings ahead, or make the chicken-and-onion base in advance and add eggs before eating for the signature silky finish.Serving ideas:Traditional Miso Soup, Japanese Cucumber Salad, Cucumber Tsukemono, Pickled Napa Cabbage